Computers at Russian state gas giant Gazprom were infected as part of a global cyber attack on Tuesday, a government official and a person investigating the incident told Reuters.

The computer virus, which researchers are calling GoldenEye or Petya, has wreaked havoc on firms around the world as it spread to more than 60 countries.

The sources gave no further details on the number of computers infected, which Gazprom systems were hit or the extent of the damage.

Gazprom declined to comment.

Russian oil major Rosneft was one of the first companies to reveal it had been compromised by the virus, which also infected computers at steelmaker Evraz. Both companies said their production was unaffected.